Insulating-bushing.



S. M. KINTNER. INSULATING BUSHING. APPLICATION FILED AUG. s, 190s.

952,448 Patented Man22, 1910.

2 SHEETS-SHEET 1.

lNvE Tow` WITNESSES:

ATTORNEY S. M. KINTNER.' INSULATING BUSHING. I

2 sEBBTssHEET 2 WITNESSES:

ythe condenser type insulation.

UNTE ltdfllldldlll @Ellllillli SAMUEL M, KINTNER, OF PITTSEURG, PENNSYLVANIA, ASSIGNO, BY MESNE ASSIGN- MENTS, T0 WESTLNGHOUSE ELECTRIC @c MANUFACTURING COMPANY, 0F EAST PITTSBURG, PENNSYLVANIA, .A CORPORATIONOF PENNSYLVANIA.

NSULATING-BUSHING. i

i To all whom it may concern:

Be it known that l, SAMUEL M. Kru'rNEn, a citizen ofthe United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful lmproveu'icnt in Insulating- Bushings, off which the `following is a specification.

iVlyhnveirnon relates to insulators for high potential electrical circ its and it has special reference to device of this character in which alternate layers of suitable insulating and ,conducting materials are employed for the purposeof providing a series of condens- .ers between the external surfaces of the insulator.l Insulation of this general type has been used in the prior art and is known as lhen this insulation is utilized for bushings or sleeves for the electrical separation of conducting leads from conducting casin'gs or tanks, in

which transformers and other electrical apparat-us are contained, it has been found de- 1 -Jirable to taper the ends of the cylindrical bushing in order to increase the surface or creepage distance between the conducting cylinders which constitute the condenser plates. It is a Well known fact' that the electrostatic leakage or discharge of electricity in the air is materially increased when the charged conductors are provided ,surface distance ,iseven greater.

with sharp points or sharp edges.

According tol' my present invention l provide an insulating bushing, constructed as above indicated, with alternate layrs of in`- sul'ating and conducting materials ibut, instead of continuously tapering the ends of the bushing, l make successive layers of insulating material ofvai'ying lengths,l thereby forming a stepped structure in which the Theends of the conducting cylinders Which are eX- posed are Wrapped over and soldered to rings of conducting material of circular cross section in order to do away with the usual sharp edges of the cylinders froml which a considerable electrostatic leakage is found to take place.

Figure l of the 'accompanying drawings is an elevation of an insulating bushing constructed in accordance With my invention, Fig. 2 is a sectional View which discloses the 'structure of the bushing shown in Fig. l and Patented Mar. 22, 1910..

pplication filed August 8, 1908. Serial No. 447,607.

| Fign is an endview, on a larger scale, of i the same bushing.

eferrilrg to the drawing, the bushing or sleeve l. which embodies my invention and'is adapted for the insulation of transformer leads or the conducting leads of other electrical devic comprises a series of substantially concentric, cylihder's il and 3 which are disposed in alterii-,ation :and are composed, respectively, of insulating and conducting material. T he vcylinders 2 and 3 are of such different lengths that the assembled buslr ing provided with tapering ends and the conducting cylinders 3 are formed of tin foil or other thin metal-r plate and are so proporvtioned that their surface areas are substantially equal andtheir extreme ends are eX- posed, Rings l of lconducting material, which are circular in cross section, are litted over each outer insulating cylinder close to the end of the next larger insulating cylinder and is electrically connected to the ex# posed end of the adiacent conducting cylinf der which is Wrapped around and soldered to it. By this means, the sharp edges of the conducting cylinders, which would otherivise encourage leakage, are merged into the rings -l which have no sharp points or edges exposed to the surrounding air. .It has been found in practice that the voltagesustaining or resisting power ofthe Whole insulating bushing is materially increased by the means just described, since the usual static leakage or discharge which tends to destroyr the insulating properties of the surrounding air is practically avoided. rlhe cylindrical surface of each step adjacent to one of the metal rings a is Wrapped with cord or rope 5 which is coated With insulating Varnish 1n orderto improve the structure of the bush ing and to\ still further increase the surface leakage distance between the conducting plates. I

lin order that the complete bushing may constitute a solid mass fromk which the air is entirelyexcluded l prefer to construct the bushing as set forth in Patent No. 858,385, granted July 2, 1907, to the Westinghouse Electric & Manufacturing Company assignee of Emil Haefely, sheets of tin foil or other suitable conducting material being interposed at desired intervals between the convelutions of the insulating material dur CII ing theconstruction of the bushing. It Will probably be found preferable, in most cases, to first build up a substantially cylindrical l bushing and afterward turn oil' the ends of the outer insulating layers in order to produce the tapered or ste ped structure illustrated in Fig. l of the drawings.

`'ihe structure described is or considerable l importa-nce and advantage when the bushing is used for the insulation of relatively high-voltage leads, since the conducting plates constitute elements of a condenser and are electro-statically charged to a greateror less degree.

Although the taperedend construction provides a material surface or creepage dis-1 tance between the exposed ends of successive conducting cylinders, if electro-static discharges are permitted to occur at these l points, the voltage-sustaining or resisting power of the surrounding air Will be materially reduced in accordance with Well known principles.

t is to be understood that structural changes may be effected within the spirit and scope of my invention and l desire that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

l. An insulating medium comprising altornate layers of insulating and conducting materials, and round rod or Wire conductors into which the exposed ends of the conducting layers are merged. l

2. An insulating bushing comprising a l plurality of substantially concentric cylin- I ders of conducting material. separated by inl sulating cylinders, and conducting rings oi substantially circular cross section into i which the exposed ends ot' the conducting cylinders are merged. 3. An insulating bushing comprising a plurality ot' substantially concentric metal I cyliiulers ot' varying lengths separated by insulating cylinders, and -comlucting rings ci. substantially circular cross section'into l which the' exposed ends of the conducting l cylinders are merged.

l-An insulating' bushing comprising plurality of concentric cylinders of conducting material separated by insulating cylinders, the metal cylinders being of substantially equal areas, and rings of circular cross section into Which the exposed ends of the conducting cylinders are merged.

' 5. An. insulating bushing comprising a plurality of continuous convolutions of suitable insulating material and se arate convolutions of conducting materia interposed in the bushing at intervals to provide a plurality of substantially concentric metal cylinders, and conducting rings of substantially circular cross section into Which the exposed ends of the conducting cylinders are merged.

6. in insulating medium comprising alternate layers of insulating and lconducting materials producing a series of condensers, and means for reducing electro-static leakage from the exposed ends of the conducting layers.

T. An insulating bushing comprising a plurality of substantially concentric cylinde'rs of conducting material separated by ini sulating cylinders, and means for reducing electro-static leakage from the exposed ends of the conducting cylinders.

8. An insulating bushing comprising a series of conducting cylinders of different lengths and a series of insulating cylinders oi ditl'erent lengths concentrically assembled iu alternation, the conducting cylinders having rounded ends to reduce electro-static leakage.

i). An insulating bushing comprising a plurality of concentrically disposed conducting cylinders of different lengths having enlarged rounded ends and a plurality of insulatin-gcylinders of different lengths concentrically and alternately disposed with returence to the conducting cylinders.

ln testimony whereof, l have hereunto subscribed my name this 30th day ot' July, 1908.

Wi t nesses:

llowaun L. Buscar, limsi-:Y lliwrs. 

